This invention relates to a track fastener assembly of the type used to anchor seats or cargo to tracks fitted to the floor of a vehicle. The particular embodiment disclosed herein is of a track fastener assembly for securing an aircraft passenger seating unit to the floor of an aircraft. Therefore the vehicle referred to throughout this application is an aircraft. It is understood that the invention relates as well to other types of vehicles such as trains, buses or the like.
Many aircraft require the capability to be differently configured to meet varying cargo and/or passenger-carrying requirements such as the removal or addition of passenger seats and/or cargo. In addition, aircraft also must have the capability to easily and quickly relocate or reposition seats and/or cargo. It is often necessary in aircraft to change the spacing between seats to increase or decrease the passenger density throughout a portion of or the entire aircraft. For example, it may be necessary to change the passenger density of a particular aircraft from its normal first class and coach density to an all-coach configuration such as might be necessary with charter operations. In addition, some aircraft, particularly those operating on late-night schedules, carry both passengers and cargo, the cargo being carried in one or more compartments normally used to carry passengers. Also driving this design is the need of aircraft manufacturers to speed their initial installation time, which is a major consideration on large aircraft with many seats.
To provide this capability, aircraft manufacturers install locking tracks that run fore and aft along the deck of the major compartments of the aircraft. These locking tracks have a slot that runs the entire length of the track along its top side. Enlarged cut-out openings are spaced at regular intervals along the length of the track to receive portions of various types of track fasteners to permit the track fasteners to be positioned along and locked into the track in order to secure passenger seats and/or cargo pallets which are themselves secured to the track fastener. These track fasteners are adjustable within the track, thereby permitting the seats and/or cargo to be repositioned or removed.
The tracks and track fasteners are designed with safety as a paramount concern. A seat or cargo container which is not securely locked into the track is subject to sudden movement which can cause injury, structural damage to the aircraft or a substantial change in aircraft balance. The track assembly must be able to safely distribute the load to the track so that an load is not transmitted through only a few load distribution points in a manner that would cause an unsafe condition. Any track fastener should also be capable of being easily installed on and removed from the locking track so the seats and/or cargo can be repositioned or removed quickly, safely and with minimal effort.
Some seat units, especially first-class seat units, have become larger and heavier in an effort to incorporate additional passenger features such as complex reclining or sleeping surfaces, in flight entertainment, work surfaces, and heavily padded upholstery. With most of prior art track fasteners, the entire fastener must be moved along with the entire attached seating unit in order to engage it in the locking position of the track. This is difficult with large and heavy seat units. Furthermore, a slight misalignment of the seat tracks or legs can make the seat difficult to move in the tracks, especially in seats having more than two legs.
Accordingly efforts have been made to provide a seat track fastener in which only the locking elements are moved in order to lock the seat to the track, without having to move the entire seat. For example, U.S. Pat. No. 5,489,172 discloses a fastening device in which a locking body which engages a track is moveable relative to the body of the fastening device such that the seat or cargo unit may be locked into place without having to shift it after it is initially positioned. However, this design is operated by a hand lever which protrudes a substantial amount vertically or horizontally from the track fitting, and the motion of the lever must be accommodated in the design of the seat.
Because seat units often have extensive exterior structure or skirting which restricts access to the mounting points, it is desirable to have a track fastener which is easily operated without requiring substantial vertical or horizontal space outside of the volume of the fastener.